978
FXUS63 KABR 311925 AAA
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
225 PM CDT Fri May 31 2024

.KEY MESSAGES...

- Saturday, there is the possibility (25-35% chance) of storms
sneaking into south central South Dakota by late afternoon and then
expanding eastward (40-50% chance) into parts of eastern South
Dakota/west central Minnesota through the overnight hours. An
isolated severe storm is possible, but the overall threat is low.

- Attention turns to Sunday. Southerly winds will transport moisture
into the region and a frontal boundary will likely be the focus for
thunderstorm development. There is a slight risk (2 on scale of 5)
of severe storms across the region. All hazards possible (wind, hail
and tornadoes).

- Temperatures are forecast to rise above normal this weekend into
next week (highs in the 80s).

&&

.SHORT TERM /THIS EVENING THROUGH SATURDAY NIGHT/...
Issued at 222 PM CDT Fri May 31 2024

Despite weak surface high pressure, a pretty well defined surface
moisture boundary combined with upper level energy rounding a broad
trough is enough to focus general showers from south central South
Dakota to northeast South Dakota/west central Minnesota this
afternoon. There is a slight (20%) chance of a rumble of thunder
across far eastern South Dakota/west central Minnesota, but no
strong storms are expected. Winds will generally be light and
variable.

The upper level pattern will be more or less zonal by Saturday. The
surface pressure pattern will remain weak through the afternoon, but
we will see a return flow pattern set up later Saturday afternoon
through Sunday morning ahead of the next low pressure system. Warm
air advection along with dewpoints returning to the upper 50s/low
60s, especially across south central South Dakota, will allow CAPE
values to rise up around 500 J/KG. Combined with weak upper level
energy and a developing LLJ into the overnight hours, there is the
possibility (25-35% chance) of storms sneaking into the south
central South Dakota counties initially by late afternoon, and then
expanding eastward (40-50% chance) into parts of eastern South
Dakota/west central Minnesota through the overnight hours. In fact,
by 00Z Sunday 50% of LREF members have CAPE > 500 J/KG and 0-500 MB
bulk shear > 30 kts over our western CWA. Therefore, a strong to
severe storm or two is certainly not out of the question. Very
uncertain on the overall extent of this convection through the
overnight as well as how long and how much cloud cover will linger
into Sunday morning.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 222 PM CDT Fri May 31 2024

The long term portion of the forecast begins on Sunday with a storm
system impacting the region. Warm air advection, along with a 30-35
knot LLJ ahead of the surface low pressure may produce showers and
thunderstorms during the morning hours. How long the morning
convection lingers in the eastern CWA may limit the severe threat
during the evening hours. An area of low pressure and associated
cold front should progress eastward across the region Sunday
afternoon through the evening hours. Strong to severe storms will be
possible along the front as instability increases to 1000 to 2000
J/kg, along with 0-6 km bulk shear values 30-40 knots. The severe
threat appears best between 22-04Z and east of the Missouri River
valley. All hazards appear possible, including tornadoes. The storms
should push east of the CWA by 6Z Monday, with a brief period of dry
conditions possible on Monday. Another storm system should progress
across the region late Monday night through Tuesday, bringing
another round of strong to perhaps severe storms.

The weather pattern beyond Tuesday favors northwest flow aloft with
mainly dry conditions. Some model guidance suggests above average
temperatures by the end of next week, while others indicate
slightly below average due to an upper level trough closer to the
region.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1227 PM CDT Fri May 31 2024

Terminals KABR,KATY,KPIR,KMBG

VFR conditions will prevail. General showers, with a low (20%)
chance of thunder, will continue to track from southwest South
Dakota through northeast South Dakota through the afternoon
hours. VCSH is included in both the KPIR and KATY TAF. Winds will
generally be light and variable.


&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&

$$

SHORT TERM...Serr
LONG TERM...SD
AVIATION...Serr